TC9WMB4FU

2007-10-19

7

(2)

Random read

A random read reads data at a specified address. A dummy write is necessary to specify an address.

In random read mode, supply a device address,

W

R/

(

= 0), and a word address after a start

condition. Unlike a byte or page write, where write data is supplied immediately, a dummy write only

specifies a word address. Then, supply a start condition and transfer a device address and

W

R/

(

= 1)

in the same way as for a current address read, to read data from the specified address.

(3)

Sequential read

A sequential read reads data sequentially from successive word addresses.

For either current address read or random read, upon receiving a start condition, a device address

and R/W (

= 1), an acknowledge (low) is placed on the SDA line, followed by the data at the address

pointed to by the internal address counter. When an acknowledge (low) is then received, the word

address is automatically incremented so that the next data is driven out.

After the last address is reached, the word address is rolled over to address 0.

Figure 9

SDA LINE

1

D

6

D

4

D

5

D

3

D

1

D

2

D

0

D

7

D

6

D

4

D

5

D

3

D

1

D

2

D

0

D

7

D

6

D

4

D

5

D

3

D

1

D

2

D

0

D

4

D

5

D

3

D

1

D

2

D

0

DEVICE

ADDRESS

R

E

A

D

A

C

K

R

/

W

D

7

A

C

K

S

T

O

P

DATA (n)

READ

DATA (n)

DATA (n

+ 1)

READ

DATA (n

+ 1)

A

C

K

DATA (n

+ 2)

READ

DATA (n

+ 2)

A

C

K

D

7

D

6

DATA (n

+ m)

READ

DATA (n

+ m)

N

O

A

C

K

Address

increment

Address

increment

Address

increment

Address

increment

Figure 8

SDA LINE

1 010

0

W

6

W

4

W

5

W

3

W

1

W

2

W

0

S

T

A

R

T

M

S

B

DEVICE

ADDRESS

W

R

I

T

E

L

S

B

A

C

K

R

/

W

W

7

WORD

ADDRESS (n)

A

C

K

A

C

K

D

7

D

6

D

4

D

5

D

3

D

1

D

2

D

0

DATA (n)

S

T

O

P

L

S

B

M

S

B

101 0

1

S

T

A

R

T

M

S

B

DEVICE

ADDRESS

R

E

A

D

L

S

B

READ

DATA (n)

N

O

A

C

K

Address

increment

DUMMY WRITE

A

2

A

1

P

0

A

2

P

0

A

1